The present invention relates to a semiconductor device and more particularly to a technique applicable effectively to a semiconductor device of a BGA (Ball Grid Array) structure wherein a semiconductor chip is flip-chip-mounted onto a wiring substrate, the semiconductor chip being fabricated using what is called a wafer process package (WPP) technique involving carrying out a package process by the application of a wafer process (pre-process).
BGA (Ball Grid Array), which is a kind of a semiconductor package, has a structure wherein a large number of bump electrodes formed by solder for example are arrayed on a main surface of a semiconductor chip with an integrated circuit formed thereon.
When mounting the BGA onto a wiring substrate, it is usually necessary that a gap between the BGA and the wiring substrate be filled with a sealing resin called under-fill resin to protect a connection between the BGA and the wiring substrate.
However, the under-fill resin is poured into the gap between the BGA and the wiring substrate by a capillary action, so if the arrangement of bump electrodes is irregular, the flow of the resin becomes non-uniform and voids not filled with the resin are formed partially, thus giving rise to the problem that the connection reliability between the BGA and the wiring substrate is deteriorated.
A countermeasure to the aforesaid formation of voids during the pouring of under-fill resin is publicly known in Japanese Published Unexamined Patent Application No. Hei 8 (1996)-97313 for example. This publication discloses a technique wherein protuberances such as dummy bumps are formed in a bump electrode-free region on a main surface of a semiconductor chip to improve the flow of sealing resin based on a capillary action.
Japanese Published Unexamined Patent Application No. 2001-15554 discloses a technique wherein plural parallel or radial grooves are formed in an insulating protective film such as solder resist which covers a surface of a wiring substrate (circuit board) with a semiconductor chip mounted thereon. When sealing resin is poured between the semiconductor chip and the circuit board, the liquid resin flows smoothly through the aforesaid grooves, so that clogging and the formation of bubbles are prevented and the formation of voids is suppressed.